How to avoid crowds and have the place to yourself for a while: Get there at 10am. Watch the Mystery Train movie downstairs, then go up to the 4th floor and watch those movies. Then go back down to the exhibit hall and start your tour upwards. The Hall of Fame movie is an hour long, so you might want to watch only some of it. If you park the Great Lakes Science Center garage next door, you can get your parking validated. Metered parking is free on weekends. Enjoy a great museum!